Thread: compound turbo set up

Originally Posted by c.h.i.e.f

The 2 actuators in parallel idea would be a slight pain to get in sync but I recon it would be interesting to try... Would there be any benefits in an external wastegate ? There is more options for gate diameters and spring preloads however the pipe work would be annoying...

I think that an external wastegate will result in less back pressure buildup and excessive EGT at the exhaust manifold (less pumping loss). It will come down to the size of your HP turbo as all the gas and heat to drive the bigger LP turbo will have to go through the HP turbo wastegate and turbine unless there is an external wastegate.

Without prior experience it is a bit of an educated guess if I have it right or a little knowledge being dangerous if wrong.

Originally Posted by slug_burner

I think that an external wastegate will result in less back pressure buildup and excessive EGT at the exhaust manifold (less pumping loss). It will come down to the size of your HP turbo as all the gas and heat to drive the bigger LP turbo will have to go through the HP turbo wastegate and turbine unless there is an external wastegate.

Without prior experience it is a bit of an educated guess if I have it right or a little knowledge being dangerous if wrong.

Nothing wrong with your educated guess.

And you have identified one of the concerns I have with using a turbo off a TD5 - turbine & housing too small for the increased exhaust flow rate.

External gates aren't cheap, so without going down that route, it would be advantageous to open up the internal waste gate port as much as practical.

Originally Posted by Bush65

Nothing wrong with your educated guess.

And you have identified one of the concerns I have with using a turbo off a TD5 - turbine & housing too small for the increased exhaust flow rate.

External gates aren't cheap, so without going down that route, it would be advantageous to open up the internal waste gate port as much as practical.

True....and I also agree the td5 turbo hot side is too small which from my testing allowed egt's higher in the rev range to go through the roof with a decrease in performance...Modifying the wastegate would help however the turbine housing on these turbos are not real flash IMHO...

I tend to agree guys re the TD5 turbo. I think if I continue with the compound set up next year I will look into using the Garrett that "The 109" is using on his motor.4BD2 turbo from memory. But for now will just run around with this set up but will definitely get the pump modded for more fuel.

Justin

Originally Posted by DRanged

I tend to agree guys re the TD5 turbo. I think if I continue with the compound set up next year I will look into using the Garrett that "The 109" is using on his motor.4BD2 turbo from memory. But for now will just run around with this set up but will definitely get the pump modded for more fuel.

Justin

For our purposes, I think a GT2559V (V for VNT or VGT) would make a good HP turbo in a compound set on a 4BD1T.

I kept the GT2256V that was on my old 300Tdi for that.

Well took it for a run up the freeway. The IP pump still hesitates badly in top gear cruising, so the electric fuel pump did stuff all.
I did try the drive pressure spring on the waste gate which was excellent . Thanks Bush

I now get a very smooth 15psi but will tweak to 20.

I think I will give the compound set up a bit more testing but the torque pulse vibrations are driving me mad. I wonder if a 6 BD1 is better.

Justin

Ok

Went through the NPR books at Isuzu and it appears that the turbo & non turbo flywheels are the same.

Saying that the truck flywheel must be lighter than a LR Isuzu flywheel as I never had the vibrations with the R380/ LT85 set up.

Looks like an inertia ring is the go ( or just buy that Rubicon)

Justin

Originally Posted by DRanged

Ok

Went through the NPR books at Isuzu and it appears that the turbo & non turbo flywheels are the same.

Saying that the truck flywheel must be lighter than a LR Isuzu flywheel as I never had the vibrations with the R380/ LT85 set up.

Looks like an inertia ring is the go ( or just buy that Rubicon)

Justin

Murray (ridjidij) has posted previously that his 4BD1T (truck) flywheel is 14.7 kg. My landie 4BD1 is 16.0 kg after at least 1 round of machining.

You could get a 4BG1 flywheel and housing http://www.klassenengine.com/PDF/Isu...er%202/4BG.pdf
Though that may be too heavy!

You know you want to swap to a 6BD1T